1. Field of the Invention
This invention relates to a wide angle lens suitable as the picture-taking lens in a large camera, for example, of 4".times.5" size.
2. Description of the Prior Art
In order that distortion, curvature of image field, etc. may be well corrected over an angle of view of 100.degree. or more, it is usually necessary to adopt a lens arrangement in which lens components are symmetrically disposed with a diaphragm interposed therebetween. As is well known, symmetrical arrangements have long since been achieved by L. Bertele. However, conventional lens arrangements of this kind have suffered from the problem that the concave lens components on the opposite outer sides tend to be bulky for the purpose of well correcting the various aberrations. More particularly, increasing the size of the divergent lens component on the image size has resulted in the disadvantage that when swing-and-tilting photography is effected with the lens mounted on a large camera, the rearmost portion of the lens touches the bellows due to the mechanism of the camera or, if not so, the marginal rays are greatly cut off or vignetting occurs to make the swing-and-tilting photograph impossible. In lenses for large cameras, it is therefore desirable to contemplate that the lens arrangement be reduced in size and the effective diameter, especially of the rearmost lens (exactly, the effective diameter of the rearmost lens surface on the tangential plane) be minimized. Also, for various reasons such as avoiding out-of-focus effects resulting from the instability of the film surface which is frequently experienced with large cameras, it is often the case with these lenses that they are used with a small aperture, whereas it is desirable to maintain the relative aperture as great as possible in order also to ensure that focusing may be accomplished with ease and accuracy.